Electrophysiological (EP) cardiac mapping is a diagnostic medical procedure for identifying locations of cardiac dysfunction within a heart. Time-varying electro-cardiogram (ECG) signals are received by electrodes contacting points along the surface of a patient's heart. The signals are processed and different metrics regarding cardiac functions are computed from the processed (ECG) signals, which are then spatially mapped onto an image of the heart. The map is then outputted for a medical professional to analyze.
The analysis of cardiac signals sometimes involves synchronizing to the timing of the ECG signals. For example, U.S. Patent Application Publication 2013/0123652, whose disclosure is incorporated herein by reference, describes a method for analyzing signals, including sensing a time-varying intra-cardiac potential signal and finding a fit of the time-varying intra-cardiac potential signal to a predefined oscillating waveform. The method further includes estimating an annotation time of the signal responsive to the fit.